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Plasma progesterone and luteinizing hormone (LH) profiles were obtained during the first ovulatory cycle of heat-stressed (HS, 35 C; n = 24) and unstressed (US, 17 to 27 C; n = 24) hens using 30-min sampling intervals beginning approximately 6 h prior to ovulation. Progesterone levels from HS hens were lower from 6 h [.07 +/- .01 (SE) versus 1.66 +/- .25 ng/mL; P = .008] to predicted ovulation (.06 +/- .006 versus .70 +/- .18 ng/mL; P = .07). Likewise, LH levels from HS hens were lower from 6 h (1.55 +/- .16 versus 3.86 +/- .34 ng/mL; P = .007) to predicted ovulation (1.63 +/- .18 versus 2.50 +/- .27 ng/mL; P = .01). Eggs from HS hens were more often laid early (less than 24 h) than eggs from US hens (71.42 versus 13.33%, respectively; P = .01), but US hens more often laid eggs of a normal oviposition interval length (24 to 26 h) compared with HS hens (73.34 versus 14.29%; P = .0005). The percentage of delayed eggs (greater than 26 h) was not different (US, 14.29 versus HS, 13.37%; P = .75) between the two treatment groups. Basal production of progesterone by dispersed granulosa cells from US hens was 97.62 +/- 16.01 ng/mL. Challenge by LH increased this to 417.50 +/- 53.38 ng/mL (P = .0001). In contrast, basal progesterone secretion by cells from HS hens was 40.25 +/- 6.60 ng/mL (P = .0001) and LH challenge failed to increase progesterone production.(ABSTRACT TRUNCATED AT 250 WORDS)

Stress in poultry is difficult to define and measure. There is general agreement that some modern poultry production practices may exert a certain amount of stress on birds. Three experiments were conducted to explore possible measures of stress associated with beak trimming and rearing schemes. Experiments 1 and 2 examined different degrees of beak trimming and rearing schemes of wire floor versus litter floor in pullet production. Experiment 3 examined the effect of beak trimming on feed consumption for 14 days after trimming. Adrenal glands of untrimmed birds were heavier (P less than .05) than those of trimmed birds at the end of the pullet growing period in Experiments 1 and 2, evidence that beak trimming reduced overall chronic stress levels. Hearts of untrimmed birds were heavier (P less than .05) than those of trimmed birds in Experiment 1. Hearts and spleens were not affected in Experiment 2. In comparisons of rearing schemes (litter versus wire), birds grown on litter floors had heavier adrenal glands and a greater incidence of cannibalism in the later weeks of Experiments 1 and 2. This indicated that a stressful interaction among penmates had occurred. Birds grown on litter floors consumed more feed than those grown on wire, and the untrimmed birds from both floor types consumed more total feed than trimmed birds. By the end of the growing period, body weights were not different in either study, indicating compensation for any early beak trimming stress. Beak trimming produced a decrease in feed intake in Experiment 3, consumption was reduced (P less than .05) in 5 of the first 8 days after trimming.

Beak trimming pullets at an early age is a widespread industry practice. There is some concern that this practice may have effects on the subsequent performance of the birds in the production phase. Effects of beak treatment (trimmed or untrimmed) and rearing floor type (litter or wire) on performance of caged layers were evaluated in a 2 × 2 factorial arrangement of treatments. Pullets that were trimmed or untrimmed at 10 days of age and reared on either litter or wire floors were placed in a cage house. Production factors and stress measurements were recorded to determine detrimental effects of the early trimming and rearing floor types. No interactions (P = .15) between rearing floor type and beak treatment were observed for BW, feed consumption, egg production, heart weight, spleen weight, or blood corticosterone. However, an interaction (P = .02) between rearing floor type and beak treatment was observed for adrenal weight. There were no differences (P = .08) in the final BW of the pullets. Birds reared on litter ate considerably (P = .0002) more than those reared on wire. There were no differences (P = .27) in egg production rate. Adrenal weights were different (P = .007), with the litter-raised birds having much smaller adrenals at the end of the 36-wk trial. Hearts of the beak-trimmed birds were smaller (P = .02) than those of the untrimmed birds. There were no differences in spleen weights (P = .07) or blood corticosterone levels (P = .07). Differences in the feather cover were observed.

1. At thermoneutrality (28 degrees C), CSF Na+:Ca2+ in hens was 61.66; under thermal stress (39 degrees C), it changed to 59.38 (30 min), 62.58 (3 hr), and 52.44 (10 hr); no change in ratio occurred at 15 degrees C. 2. ICV Ouabain and/or EGTA increased body temperature (TR) but not respiration rate (RR) at 39 degrees C. 3. At 28 degrees C, Ouabain decreased, and EGTA increased, TR and RR. 4. Ca2+ may be more critical than Na+ in thermoregulation. 5. Heat stress appears to stimulate Na+-transport mechanisms other than Na+-ATPase. 6. RR appears to be a function of TR, not of ion balance.

It is well documented that feed intake theories developed from research with other species are applicable in some form in the avian species. One of the first places that application of feed intake principles appears in the literature is in the science of nutrition. By the early 1950’s some nutritionists had begun to report nutrient requirements on a daily intake basis. In 1971, the National Research Council (NRC) listed nutrient requirements both as percentages of the diet and daily intake needs. In 1981 the NRC published a special bulletin entitled “Effect of Environment on Nutrient Requirements of Domestic Animals.” Although nutritionists have always been more or less aware of the influence of feed consumption on ration content needs, it is clear that the development of related knowledge has tended to heighten awareness of the need to carefully consider feed intake in ration formulation. Poultry management specialists and applicators have also developed interest in feed intake considerations. Today, the better managers (especially egg production managers) maintain accurate feed intake records along with time of hatch (age) and environmental notes to relate to production level. These data are analyzed sometimes by hand, but often by computer, and used to make daily or weekly adjustments in feed formulation, ventilation rate, and in some instances housing density and other management decisions.

Two experiments using 64-week-old Single Comb White Leghorn roosters were conducted to determine the meal response to an abrupt change in dietary energy or environmental temperature. In the first experiment, dietary energy level was changed from 200 kcal to either 250 or 150 kcal/75 g. In the second experiment, environmental temperature was changed from 22.2 C to either 13.3 or 30.0 C. Feeding behavior was recorded throughout both experiments. Meal size, meal frequency, and time spent eating a meal were measured. Roosters changed to high-energy or low-energy diets consumed low or high amounts of feed, respectively. Those fed the high-energy diet tended to decrease meal size and meal duration and to increase the number of meals. Roosters changed to the low-energy diet decreased meal size and meal duration and increased the number of meals eaten. The results tend to confirm the chemostatic mechanism in birds as food intake was related to energy in the diet. Roosters changed to high or low environmental temperature responded by decreasing or increasing their feed intake, respectively. Roosters changed to a high environmental temperature significantly decreased meal size, meal duration, and increased the number of meals. Those changed to a low environmental temperature significantly increased meal size and decreased meal frequency and meal duration.

This experiment was conducted to better estimate the minimum protein and energy requirements of the laying hen at different production levels. The experiment was also designed to estimate the maintenance level of energy and protein, and to ascertain the amounts of protein and energy needed to produce an egg. Egg production levels of 4.2, 29.8, 49.1 and 70.5 percent were actually obtained with hormonal therapy (progesterone). The effects of egg production level and dietary energy level on feed consumption were statistically significant. As egg production increased feed intake increased and as energy level increased feed intake decreased. The low producing hens (4.2 percent) consumed an average of 9.3 grams of protein and 182 Kcal. M.E. per bird daily. The 29.8 percent producing hens consumed 2.1 grams of protein and 45 Kcal. M.E. more than the 4.2 percent hens. The increase in egg production from 29.8 to 49.1 percent required an additional 1.1 grams of protein and 23 Kcal. M.E. As egg production increased from 49.1 to 70.5 percent, an additional 1.0 grams of protein and 19 Kcal. M.E. were needed. The maintenance requirement was estimated to be 6.1 grams of protein and 156 Kcal. M.E. per hen per day. It appeared that 15 grams of protein and 299 Kcal. M.E. per hen per day would be adequate for birds producing 80 percent or more. As egg production declined to 70 percent, 13.5 grams of protein and 269 Kcal. M.E. seemed adequate. Finally, when production declined to 50 percent, 12.5 grams of protein and 250 Kcal. M.E. per hen per day appeared to be sufficient.

twenty-week experiment was conducted to determine if dietary levels of calcium, protein and energy act or interact to influence feed intake, egg shell quality and hen performance. The design was a 5 replicate, 3 × 3 × 3 factorial arrangement of 27 treatments composed of three levels each of calcium (1.8, 3.6 and 54. g.), protein (13, 16 and 19 g.), and metabolizable energy (200, 250, 300 kcal. M.E.) in 120 g. of feed. Hy-Line W-36 hens, 31 weeks old, were used. Egg production level was significantly influenced by dietary protein, energy and calcium, under the winter-time conditions of this experiment (October 18 to March 6). According to the overall treatment means, average egg production was best with diets containing 19 g. protein, 200 kcal. M.E. and 5.4 g. calcium. Voluntary feed intake was significantly influenced by dietary energy and protein (as protein level was increased egg production increased and consequently feed intake increased) but not by calcium. However, the hens fed diets containing 1.8 g. of calcium consumed as much feed as hens fed the 5.4 g. diets even though they produced 7.9 percent fewer eggs. This may indicate that hens fed rations low in calcium consumed more feed in an attempt to take in more calcium. Breaking strength of the egg shells increased significantly as dietary calcium was increased.

INCREASING quantities of supplemental fat are being used in poultry rations as a source of energy. As a result, numerous problems have been encountered under practical feeding conditions in handling mixed feeds which contain large amounts of fat. Maximum fat digestibility would require that a minimal amount of supplemental fat be used in a poultry ration to obtain the desired energy level. For this reason, it would be desirable to find ways to increase the digestibility of supplemental fat in poultry rations. It is known that certain emulsifying agents increase the digestibility of fat by both rats (Augur et al., 1947) and chicks (Fedde et al., 1960). Observations from the field and the results of feeding trials at the Oklahoma Agricultural Experiment Station indicate that when Yeast Culture3 was added to rations fed to growing turkeys there was an increased growth rate. It was postulated that the increased growth might…

THE effects of varied dietary levels of protein, energy, vitamins and minerals upon the performance of laying hens have been studied by many research workers including Berg et al. (1952), Ringrose et al. (1954), Heywang et al. (1955), Thornton et al. (1957), Adams et al. (1958), Hill et al. (1956), Anderson et al. (1957), Bolton (1958), Petersen et al. (1960), Thayer et al. (1956), Touchburn and Naber (1962), and Gleaves et al. (1961). The results obtained from these experiments have often been contradictory and confusing. For example, Berg et al. (1952), Thornton et al. (1957), and Adams et al. (1958) report that a dietary protein level of 13 percent is sufficient to maintain egg production, egg weight and body weight. On the other hand, Ringrose et al. (1954) and Heywang et al. (1955) state that 15 percent of dietary protein is adequate. Many possible explanations are given for such discrepancies . . .

THERE is evidence in the literature which indicates that the control of nutrient intake to provide an adequate but not excessive quantity of each nutrient increases longevity, decreases susceptibility to disease and controls body weight (Berg, 1960; Berg and Simms, 1960; Singsen et al., 1958). Where nutrients are supplied ad libitum rather than on a restricted basis, there is a tendency to decrease the deposit of body fat, increase the retention of protein and increase the activity of the thyroid (Cohn et al., 1961; and Hollifield and Parson, 1962). Physiological mechanisms which involve dietary volume in the regulation of feed intake were reported by Janowitz and Grossman (1949). These physiological mechanisms, activated by dietary volume, were utilized by Gleaves et al. (1963) to regulate nutrient intake when hens were fed ad libitum. Accurate dietary volume values must be obtained for feed ingredients if dietary volume is to be used in…

Hy-Line 934 F pullets 28 weeks old were individually caged and fed nine different 120 g. diets containing all combinations of 10, 13 and 16 g. of protein and 200, 250 and 300 kcal. of metabolizable energy in two experiments. The first experiment included normal and ovariectomized pullets under uncontrolled environmental temperature. The second experiment included normal and progesterone injected pullets under controlled environmental temperature. Feed consumption was measured and the protein and energy intakes were calculated. Both experiments ran for 28 weeks. Average production was 0.189, 0.086 and 0.74 eggs per hen per day for the ovariectomized, progesterone injected and normal hens, respectively. Body weight gain was 0.66, 0.69 and 1.14 g. per hen per day for the respective treatments. Feed intake levels were significantly different at each energy level. There was no significant effect of protein upon feed intake. Egg production for normal and “non-laying” hens increased significantly with each increase in dietary protein. Average protein intakes as low as 6.0 g. per day and energy intakes as low as 144 kcal. M.E. in 50 g. of feed (300 kcal. diets with sand and solka-floc removed) were adequate for hens adjusted to zero egg production. Except for the influence of varied dietary energy levels, these estimates compare reasonably well with calculated projections using partition equations derived by Titus (1928) and Brody et al. (1938).

MILO and corn are two of the principal grains available for use in the formulating of poultry diets. Semi-arid climatic conditions in many areas of the Southwest make it very difficult to raise corn, but large quantities of milo are produced. For this reason, the price of milo in these areas is substantially lower than the price of corn. This leads to the extensive use of large quantities of milo in poultry diets. A major problem encountered in this situation is one of determining, from a nutritional standpoint, how much milo can be used efficiently in these poultry diets. Published research data indicate that milo and corn give similar results in poultry diets when the differences in nutrient content of the two grains have been taken into consideration in the formulation of the diets. Hammond (1942) reported that either yellow milo or hegari is equal in value to white corn…

MANY interrelationships are encountered in studying amino acid requirements of animals. Because of this fact, methods which employ only the productive performance of an animal to determine dietary needs rapidly become inadequate when more than one or two amino acids are considered at a time. Any method which would aid in interpreting the amino acid interrelationships would be a tremendous step toward establishing a more efficient balance among the dietary amino acids for poultry. While a review of the literature on blood amino acid studies in other species provides limited supporting evidence, it seemed a reasonable possibility that with turkeys growing at the rate and with the efficiency of feed conversion obtained by Dunkelgod et al. (1961), the concentrations of amino acids in the blood might be correlated with dietary requirements. Richardson et al. (1953) added methionine and lysine separately and in combination to a diet deficient in both of…

REVIEW OF LITERATURE FOR a long time it has been known that lysine and methionine are two of the most limiting amino acids in poultry feeds. Working with individual amino acids numerous workers have shown that supplementary lysine can improve the performance of birds fed low protein diets [Thorton et al. (1957), Waibel and Johnson (1961), Bradley and Quisenberry (1961), Harms and Waldroup (1962), and Sell and Hodgson (1966)]. Methionine supplementation on the other hand appears to be more beneficial at higher protein levels or in low protein diets which have already been supplemented with lysine (Barton and Stephenson, 1960; Harms and Waldroup, 1962; Sell, 1964; and Daghir et al., 1964). Biely and March (1964) and Smith (1967) have also demonstrated that supplementation with both lysine and methionine results in greater production, hatchability, egg size, egg weight and feed efficiency than with either amino acid. A third limiting amino acid…

RESEARCH studies in the field of physiology have established the fact that certain specific physiological mechanisms in animals regulate and maintain energy balance. Such regulation and maintenance are brought about through adjustments made in four important variables: (1) food intake, (2) stored energy, (3) work, and (4) heat production. Food intake is the key factor in this regulating process, since it compensates for any changes in the other three variables. For this reason, the mechanisms that regulate food intake are of prime importance in the overall maintenance of energy balance (Anand, 1961). During the past 20 years, the physiological regulators of food intake have been studied more and more as functions of the central nervous sytem (Grossman, 1963). From the research data acquired in these studies, five food intake regulatory mechanisms have been proposed as signals for the central nervous system. These are: (1) the “thermostatic” hypothesis of Strominger and . . .

RESEARCH data indicate that the daily feed consumption of laying hens depends primarily upon the levels of dietary protein and energy. Laying hens have the ability to compensate for low levels of dietary protein and energy by consuming more feed; and similarly, hens that are fed extremely high levels of protein and energy compensate by consuming less feed. This ability of the laying hen to regulate nutrient intake, by varying feed intake, has contributed greatly to the confusion over the exact percentages or proportions of nutrients required in laying hen diets. A comparison was made of the protein and energy intakes of laying hens at the Oklahoma Agricultural Experiment Station, when layer rations with graded levels of dietary energy and protein were fed. This comparison revealed that approximately 16 grams of protein and 300 kilocalories of energy were consumed per hen per day, regardless of the ration which was fed.…

INTRODUCTION DIETARY protein, energy, weight and volume all have been found to exert a significant linear effect upon feed consumption of laying chickens (Gleaves et al, 1968). However, the existence of several significant interaction effects demonstrated that the dietary factors were not independent of one another. The purpose of the experiments reported herein was three-fold. The first was to reexamine the effects of dietary protein, energy, weight and volume upon feed consumption and production characteristics of laying hens, under different environmental conditions and with a less complex factorial arrangement of treatments. The large factorial (34) used by Gleaves et al. (1968) was broken into small factorials (32) to permit a closer examination of the main effects of the four dietary factors without the interference of so many interactions. Even though the interactions might be present, they should not confound the main effects as much in smaller factorials because fewer factors would…

VITAMIN requirement standards for laying hens are incomplete. A review of the literature reveals that very little experimental work has been done on vitamin requirements and vitamin interrelationships. Riboflavin and niacin are two of the vitamins which have received relatively little attention in requirement studies. Relatively little work has been published on the niacin requirements of laying hens, and the research data on riboflavin requirements are contradictory. Several attempts were made before 1950 to determine the quantitative requirements of laying hens for riboflavin. Davis et al. (1938) obtained normal production with a ration which contained 0.454 mg. per lb. (computed by them to contain 100 Cornell units per 100 gms.). Cravens et al. (1946) fed rations that varied from 1.3 to 1.9 mg. of riboflavin per lb. of finished ration. Based on data obtained in these trials, it was concluded that there were no significant differences in egg production between…

FEEDING standards for turkey poults are commonly based upon percentages or other proportional units of a prepared feed. While this method has obvious advantages, it does not take into account specific daily nutrient requirements. Furthermore, this method of determination does not offer an adequate basis for the consideration of nutrient interrelationships and nutrient balance. It is believed that these limitations have contributed greatly to the wide variation in nutrient allowances as currently recommended for growing turkeys. There appears to be a critical need to establish a more realistic basis for the determination of feeding standards. A need to determine nutritional requirements on a daily intake basis was first encountered in human nutrition. As early as 1921, Holt and Fales indicated that caloric requirement could be more adequately expressed as caloric intake per day per kilogram of body weight rather than other allowances. Cowgill (1928) emphasized the importance of daily nutrient …

SEMI-PURIFIED experimental turkey starter and grower diets which were developed at Oklahoma State University made it possible to produce a pound of market turkey on 2.2 pounds of feed (Thayer et al., 1961). The data from this feeding trial were used as a nutrient standard, and a linear programming program with an electronic computer was employed to formulate starter diets which contained practical feed ingredients. These practical type starter diets were formulated to be the equivalent in protein, amino acids and energy of the original semi-purified starter diet. Daily nutrient intake standards were developed for males and for females for each successive week of the growing period. These daily nutrient intake standards were utilized in modifying the starter diets into a series of grower diets. The practical type grower diets developed in this manner were fed to growing turkeys during an entire growing period from day-old to market weight. The…

REVIEW OF LITERATURE Supplementation of poultry feeds with fungal-bacterial enzymes was reported early by Hastings (1946). His results with broilers showed a net gain of six ounces (170 grams) and a saving of 0.5 pounds (227 grams) of feed per pound (454 grams) of bird with enzyme added to high-fiber mash. Ely (1963) reported data involving more than 150,000 layers fed corn and milo rations in which fungal-bacterial enzymes improved post-peaking egg production 3 to 5 percent and reduced feed required per dozen eggs by 2.5 to 4 percent. Petersen and Sauter (1968) obtained variable results from two commercial enzymes when added to either a barley or corn and barley ration fed to laying hens. Egg production was higher in the enzyme-fed hens than in controls, but was significantly improved in only one of the three experiments. Hatch of fertile eggs was also significantly improved. Berg (1961) and Anderson et. . .

An experiment was conducted to study calcium appetite and dietary calcium level related to laying hen performance. The experiment consisted of three periods: pre-experimental, training, and experimental. A total of 80 commercial strain laying hens (58 weeks old) were divided into two groups. One group (20 birds) served as a control throughout the experiment and was fed 3.5% dietary calcium without a free-choice calcium supplement. The other 60 birds were randomly divided into 3 sets of 20 and were all fed 3.5% dietary calcium for a pre-experimental period (13 days) as an adaptation period to a new environment prior to a training period (5 weeks). Dietary calcium level was decreased by .5% each week through the 5th week (to 1% Ca) for all 60 hens during the training period. The birds were given access to a free-choice calcium supplement (calcium carbonate granules) during both the pre-experimental and training periods. This dietary regimen was used in an effort to allow all hens to adapt to a supplemental feeding program and be prepared or conditioned for sudden changes in dietary calcium level. At the end of the training period, the 3 sets of 20 hens were fed either 1, 3, or 5% dietary calcium and a free-choice calcium supplement for 6 weeks. As dietary calcium level was increased, there was a decrease in free-choice supplemental calcium intake; however, all birds (except controls) consumed very large amounts of calcium. The training procedure was successful: no hens rejected the supplement. Neither dietary calcium level nor total calcium intake affected feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Two environmental temperatures, 21 and 30 C, were used during a 28-day experimental period. There were two groups of hens in each temperature treatment. The control groups (C) were given a conventional balanced diet and each dietary self-selection group (S-S) was provided, on an individual hen basis, three diets each one being high in energy, protein, or calcium. The S-S groups had significantly reduced egg production, which probably resulted from the significantly reduced protein intake. Egg weight and energy intake were reduced in the S-S group at 21 C while calcium intake and egg shell strength at 30 C were higher as compared to the corresponding C group. Dietary self-selection did not enable hens to regulate nutrient intake for comparable performance to hens provided one balanced diet. Also, the detrimental effects of high environmental temperature were not overcome by dietary self-selection.

This research was designed to provide information regarding the role of environmental temperature and dietary energy in the control of feed intake. Seven-month-old laying hens were individually caged in two environmental chambers for 18 weeks in Experiment 1. A 2 × 2 × 2 factorial design was used with dwarf and normal stock, 22 and 30° C. environmental temperatures, and two dietary energy levels of 250 and 350 kcal. metabolizable energy (M.E.) per 114 gm. (2193 and 3070 M.E. kcal./kg.) of feed. The high energy diet and also the high environmental temperature decreased the feed intake of dwarf and normal hens. Actual energy intake was not affected by different dietary energy levels but high environmental temperature decreased the actual energy intake in normal and dwarf birds. Egg production was adversely affected by high dietary energy levels, but not by high environmental temperature. Body weight change was negatively affected by high environmental temperature. Experiment 2 was conducted with six-month-old roosters to eliminate the variable of egg production. The study was conducted for 12 weeks in a manner similar to Experiment 1 except that three dietary energy levels were used. The results were found to be in close agreement with Experiment 1, except that no significant difference in body weight change was noted either due to environmental temperature or dietary energy. The results of this research indicate that the thermostatic and chemostatic mechanisms for control of feed intake are operative in chickens and that both have a negative relationship to feed intake.

1. Hens received ICV injections of Ca2+ (1.98 g/100 ml) or Na+ (7.25 g/100 ml) at 28 degrees C and, following acclimation, at 37 or 20 degrees C, respectively. 2. At 28 degrees C (thermoneutrality), rectal temperature rose (P less than 0.05) following Na+ and fell (P less than 0.05) following Ca2+, similar to mammals and broiler chickens. 3. At 37 degrees C, Ca2+-induced hypothermia did not occur; nor did the Na+-associated hyperthermia at 20 degrees C. 4. Acclimation to a high or low temperature may produce an endogenous shift in CSF ion levels that make additional ion administration ineffective in affecting body temperature.

The objective of this study was to determine the response characteristics of feed intake following an abrupt change in environmental temperature or dietary energy. A 2 x 2 factorial design was used with 23 and 30° C. environmental temperatures and dietary energy levels of 200 and 300 kcal. metabolizable engery (M.E.) per 120 gm. feed. Five months old roosters were maintained in individual cages. After receiving the treatments for seven months the environmental temperatures were abruptly switched (23 to 30 and 30 to 23° C). Eight weeks later the diets were abruptly switched (200 to 300 and 300 to 200 M.E. kcal.). Significant differences in feed intake due to environmental temperature and dietary energy existed prior to the switches. The switch of environmental temperatures resulted in an immediate inverse change in feed intake. The magnitude of the difference due to temperature was less after the switch than before. An immediate inverse change in feed intake also resulted when the diets were switched. However, in this case the magnitude of the difference due to diet was almost the same after the switch of diets as before. Thus, abrupt changes in dietary energy caused a more marked and precise response in feed intake than abrupt changes in environmental temperature. From this study it was concluded that the thermostatic and chemostatic mechanisms exert control over feed intake not only on a short term basis but also to some extent on a long term basis. With the temperature and dietary energy treatments used in this study, the effect of the chemostatic mechanism was more pronounced than the thermostatic mechanism in controlling feed intake. Heat increment of the feed appeared to be more involved with the cessation than the initiation of feeding.

Three experiments involving a total of 550 laying hens were conducted to study the effects of low level lactose feeding on the egg production characterisitcs of laying hens. The specific purposes were to determine if lactose influenced calcium utilization and feed intake and if there were any important interactions between lactose and calcium. There was a consistent significant improvement in egg shell breaking strength as a result of lactose supplementation. One percent dietary lactose appeared to be adequate to achieve this improvement. The addition of 2 or 3% lactose did not result in any greater improvement than 1%. There were no consistent influences of lactose, lactose source, or calcium level on feed intake or any of the other variables examined in the three experiments. As was expected, 61-week-old hens laid significantly fewer and larger eggs with weaker shells than 47-week-old hens. There were four statistically significant interaction effects: lactose level × calcium level on egg production; lactose level × calcium level on egg shell strength; and age × lactose level on egg shell strength. Even though these effects were statistically significant, it is questionable whether or not they are of practical importance in feeding laying hens.

THE PHYSICAL and chemical properties of the feed which are related to nutrient intake, including feed weight, feed volume, feed energy and feed protein, have been given special emphasis in studies reported by Gleaves (1961), Dunkelgod et al. (1961, 1962), Gleaves et al. (1963a), Ozment et al. (1963) and Gleaves (1963). The physiological mechanisms through which the action of these four factors are directed in regulating food intake have been discussed in detail in a review paper by Anand (1961). However, little data are available in the literature on the application of these four factors, either singly or in combination, upon nutrient intake when practical rations are fed to growing turkeys. The experiment reported in this paper was designed to study some of the qualitative relationships of nutrient density (expressed as units of nutrient per unit of feed weight) to the daily intake of feed weight, feed volume, feed energy…

A LITERATURE review summarizing available research data on restricted feeding programs for replacement pullets has been made by Wolf (1965). The data which have been obtained are often inconsistent and contradictory. A more basic approach needs to be made in studying the nutrient intake requirements of replacement pullets in which consideration is given to food intake and the factors which control food intake. The individual physiological mechanisms through which food intake is regulated and controlled have been summarized in a review paper by Anand (1961). The basic findings from this area of research (insofar as they involve dietary protein, dietary energy, dietary volume, and dietary weight) have been applied in the feeding trial with replacement pullets which is reported in this paper. EXPERIMENTAL PROCEDURE General Design. The experimental design and the treatments imposed in this experiment are outlined in Table 1. The entire experiment covered a span of 64 weeks…

A cooling device was developed to prevent the rapid breakdown of the quality of broken-out eggs displayed in open air educational settings. This device consists of a plastic container that holds a freezeable jell. Blue ice. Loose polystyrene is utilized for insulation. A petri dish set on the container lid will hold a broken-out egg. Egg quality can be held over a sufficient period of time for education or contest purposes.